Understanding the Heart Sutra
Ven. Sangye Khadro

The Heart Sutra is a member of the Perfection of Wisdom (Prajñāpāramitā) class of Mahāyāna Buddhist literature, and along with the Diamond Sutra, is considered to be the primary representative of the genre. It consists of just 14 shlokas or verses in Sanskrit and 260 Chinese characters in the most prevalent Chinese version, Taisho Tripitaka Vol. T08 No. 251, translated by Xuan Zang. This makes it the most highly abbreviated version of the Perfection of Wisdom texts, texts which exist in various lengths up to and including 100,000 slokas. This sutra is classified by Edward Conze as belonging to the third of four periods in the development of the Perfection of Wisdom canon, although because it contains a mantra (sometimes erroneously called a dharani), it does overlap with the final tantric phase of development according to this scheme.
The study of the Heart Sutra is particularly emphasized in the practice of East Asian Buddhism. Its Chinese version is frequently chanted (in the local pronunciation) by the Chan, Zen, Seon and Thiền sects during ceremonies in China, Japan, Korea, and Vietnam respectively. It is also significant to the Shingon Buddhist school in Japan, whose founder Kukai wrote a commentary on it, and to the various Tibetan Buddhist schools, where it is studied extensively.
A striking feature of the sutra is the fact that the teaching is not actually delivered by the Buddha, which places it in a relatively small class of sutras not directly spoken by the Buddha.